See if this works for you:
AMD Athlon II X2 240 (2.8GHz)
Gigabyte GA-MA74GM-S2 (AMD 740G)
Above Processor + Motherboard = ~Rs.5,500/-
Corsair VS2GB800D2 RAM (DDR2 800MHz) = ~Rs.2,100/-
Western Digital Caviar WD5000AAKS HDD (500GB SATA) = ~Rs.2,400/-
Samsung/LG 22X DVD Writer = ~Rs.1,150/-
Zebronics Bijli Cabinet (Incl. PSU) = ~Rs.1,700/-
Total: Rs.12,850/- Approx. (+/- a few hundred Rupees)
In case you want to opt for an Intel based solution, You only need to swap the CPU & Motherboard keeping the rest of the components same:
Intel Dual Core E5400 CPU (2.7GHz) = ~Rs.3,000/-
Intel DG41RQ (G41 LGA775) = ~Rs.2,900/-
Total ~Rs.5,900/-
For a DDR3 RAM based combo, opt for the following:
Intel Dual Core E5400 CPU (2.7GHz) = ~Rs.3,000/-
Gigabyte GA-G41MT-ES2L (G41 LGA775) = ~Rs.3,000/-
Corsair/G.Skill 2GB 1333MHz DDR3 RAM = ~Rs.2,700/-
Rest of the components remain same.